1. Field of the Invention
This invention relates in general to video signal processing and, more particularly, to apparatus and techniques which, by their adoption, facilitate the design and use of portable video cameras. The invention may be embodied in color video cameras, as well as in black-and-white video cameras.
2. Description Relative to the Prior Art
Aside from relatively large studio video cameras, various portable video cameras are beginning to appear in the trade. Such portable video cameras are characterized, usually, by a hand-held camera unit and a complementary unit which is usually worn as a back-pack, or the like, by the camera user. The hand-held camera unit serves as an image sensor; and the complementary `back-pack` unit (1) serves as a recorder, (2) provides power for both the recorder and camera units, and (3) provides control signals for operating the camera unit and recorder. The actual image sensor of the camera unit, which sensor may, for example, be a vidicon, is operated at reference horizontal and vertical sweep frequencies; and the recorder, which typically is a video magnetic tape recorder, provides relatively precise speed control between its recording head(s) and tape. The precision tape-to-head(s) speed control is dictated by the magnetic tape playback function; i.e., in order to reconstruct, say on the face of a television picture tube, the video image seen by the sensor of the camera unit, it is necessary to replay the recorder tape at the same speed as was employed during the recording operation.
Video tape playback apparatus customarily drives magnetic tape at a precise predetermined speed. Thus, it has been incumbent, as in a portable video camera, for the video tape recorder thereof to control precisely its recording speed to the abovereferred to predetermined playback speed, for otherwise meaningful playback of camera-recorded images would be impossible. Requirements such as this have militated against the packaging of a video camera into a format resembling a conventional movie film camera. In other words, to embody a tape recorder having a precision tape drive -- and all that entails -- into a video camera is, almost by definition, akin to saying that the camera so produced is one that cannot be hand-held.